Electrical conductor for a stator of a rotary electric machine, and method for manufacturing same

Abstract

The invention relates to an electrical conductor for a stator of a rotary electric machine, in the form of a U-shaped hairpin, having: —first and second legs intended to extend axially in a first slot A and a second slot R, respectively, of the stator, —a bundle portion connected to the first and second legs of the electrical conductor in each case by an oblique portion, —the two oblique portions being in the form of a helical portion.

1 . A stator of a rotary electric machine, comprising a stator mass comprising slots, electrical conductors accommodated in the slots, the stator comprising two electrical conductors per slot,
 at least a part of the electrical conductors, or even a majority of the electrical conductors, more preferably all the electrical conductors, being U-shaped, comprising several strands, the electrical conductor comprising:
 first and second legs intended to extend axially in first slot A and a second slot R, respectively, of the stator, the strands of the first leg being arranged in the first slot in a radially inverse order to the strands of the second leg in the second slot, 
 a bundle portion connected to the first and second legs of the electrical conductor in each case by an oblique portion ( 22   b ,  22   c ), 
 the two oblique portions ( 22   b ,  22   c ) being in the form of a helical portion. 
   
     
     
         2 . The stator according to  claim 1 , comprising three strands. 
     
     
         3 . The stator according to  claim 1 , wherein the thickness (B) of the electrical conductor at the bundle portion is substantially equal to the thickness of the strands of the electrical conductor, in particular very slightly greater. 
     
     
         4 . The stator according to  claim 1 , wherein the length (C) of the bundle portion measured between the two oblique portions is less than 3D, where D is the median pitch corresponding to the gap between two consecutive slots of the stator. 
     
     
         5 . The stator according to  claim 1 , wherein the height (H) of the bundle portion relative to the first and second legs is less than 70 mm. 
     
     
         6 . The stator according to  claim 1 , wherein the length (C) of the bundle portion measured between the two oblique portions substantially corresponds to the sum of the width of a strand added to the median pitch (D), which corresponds to the gap between two consecutive slots of the stator. 
     
     
         7 . The stator according to  claim 1 , wherein the first leg is arranged closer to the rotor than the second leg. 
     
     
         8 . The stator according to  claim 1 , wherein an outer diameter of the set of electrical conductors of the stator, defined by the bundle portions, is smaller than the outer diameter of the slots plus 0 to 6 times the thickness of a strand. 
     
     
         9 . A rotary electric machine comprising a stator according to  claim 1  and a rotor. 
     
     
         10 . A method for manufacturing an electrical conductor for a stator of a rotary electric machine, comprising the following steps:
 (a) providing a bundle of one or more strands bent into a U, the strands in particular being bent flat, the bundle folded into a U comprising a bundle portion and two legs,   (b) separating the two legs in order to form two rectilinear oblique portions, the separation being carried out in two opposite directions parallel to the flat of the strands,   (c) folding back the oblique portions inwards, so as to form first and second legs of the electrical conductor each connected to the bundle portion by a rectilinear oblique portion, the first and second legs extending parallel to one another.   
     
     
         11 . The method according to  claim 10 , wherein, during the separation step (b), the bundle folded into a U-shape is channeled at the apex of the U by applying pressure under the bundle in the bottom of the U. 
     
     
         12 . The method according to  claim 10 , wherein the bundle portion is not held during the separation step (b). 
     
     
         13 . The method according to  claim 10 , wherein in step (a), the bundle is folded about a shape part. 
     
     
         14 . The method according to  claim 10 , wherein in step (c), the rectilinear oblique portions are held on the one hand, and the first and second legs are held on the other hand in order to fold them inwards relative to the rectilinear oblique portions. 
     
     
         15 . The method according to  claim 10 , comprising the following additional step:
 (d) curving the oblique portions, according to the contour of the stator, the oblique portions becoming a helical portion.   
     
     
         16 . The stator according to  claim 1 , wherein the length (C) of the bundle portion measured between the two oblique portions is less than 2D, where D is the median pitch corresponding to the gap between two consecutive slots of the stator. 
     
     
         17 . The stator according to  claim 1 , wherein the height (H) of the bundle portion relative to the first and second legs is less than 30 mm. 
     
     
         18 . The stator according to  claim 1 , wherein an outer diameter of the set of electrical conductors of the stator, defined by the bundle portions, is smaller than the outer diameter of the slots plus four times the thickness of a strand. 
     
     
         19 . The method according to  claim 10 , wherein in step (a), the bundle is folded about a bending dowel.